Apparatus for mixing of bleaching agents into cellulosic pulp



Jan. 30, 1968 o, TQFTE 3,366,367

APPARATUS FOR MIXING OF BLEACHING AGENTS INTO CELLULOSIC PULP Filed Feb. 28, 1966 United States Patent APPARATUS FOR MIXING 0F BLEACHING AGENTS INTO CELLULOSIC PULP Arve Olav Tofte, Karlstad, Sweden, assignor to Aktiebolaget Kamyr, Karlstad, Sweden, a company of Sweden Filed Feb. 28, 1966, Ser. No. 530,483

Claims priority, application Sweden, Mar. 5, 1965,

4 Claims. (Cl. 259) ABSTRACT OF THE DISCLGSURE An improved mixing apparatus utilizes a rotary vane wheel to mix a bleaching agent into successive layers of cellulosic pulp as the pulp is rotated past an inlet through which the bleaching agent is introduced. The bleaching agent inlet may have the configuration of a narrow sector of a circular zone on a plane past which the rotary vane wheel sweeps, and the pump may be delivered into and out of the rotating vane wheel through orifices which are essentially coextensive.

The invention relates to an apparatus for mixing of bleaching agents into cellulosic pulp, particularly highdensity pulp, by means of a rotary vane wheel towards which pulp supplied through a pulp inlet is conveyed in such a manner as to bring the pulp to pass axially between the vanes While taking part in the rotation of the vane wheel.

The object of the invention is to cause successive layers of the pulp supplied through the pulp inlet to move with a great velocity past an orifice through which a bleaching agent is supplied, in order thereby to spread the bleaching agent into the pulp evenly and efficiently. The characterizing feature of the apparatus according to the invention whereby said object is reached, consists in that a casing surrounding the vane wheel comprises a plane wall perpendicular to the axis of the wheel and situated closely up to the vane Wheel and laterally of the pulp inlet, the orifice of a bleaching agent inlet being located in said wall and the vane wheel being arranged to move the pulp with the full speed of the Wheel along said wall and past said orifice.

Other features of the invention will appear from the following description of an embodiment of a mixing apparatus which is shown in the accompanying drawing and to which the invention is applied. FIG. 1 is a longitudinal sectional View taken along the broken line I--I in FIG. 2, and FIG. 2 is a cross-sectional view taken along the line IIII in FIG. 1.

The mixing apparatus comprises a rotary vane wheel 11 inserted in a surrounding casing 13. The hub 15 of the vane wheel is keyed to a shaft 17 supported by ball bearings 19, 21 and the end 23 of which is adapted for connection to a motor. A number of vanes 25 preferably integral with the hub project outwardly therefrom. Each of said vanes has the shape of a thin fiat plate with two opposite rectangular broad faces and three narrow edge faces 27, 29, 31. The edge faces 27 of all the vanes are situated in one and the same plane which is perpendicu lar to the axis and also coincides with one plane end face of the hub of the vane Wheel. The same applies to the edge faces 31 at the opposite end of the vane wheel. The vanes may be truly radial, preferably however, they are directed somewhat forwardly in the direction of rotation of the vane wheel, as indicated by the arrow 33 in FIG. 2, so that they are tangentially or radially-tangentially attached to the hub 15. The edge faces 29 run parallelly to and all at the same distance from the axis so that they all describe the same cylindrical surface during the rotation of the vane wheel.

The casing 13 is composed of two symmetrical halves joined by means of a flange connection 35. On opposite sides of and next to the plane of division the casing has a cylindrical wall 37 which is concentric to and closely surrounds the vane wheel so that merely a very small interspace 39 is formed between said wall 37 and the parallel edges 29 of the vanes. Perpendicular to the cylindrical wall 37 and to the shaft of the vane wheel there are two plane parallel walls 41, 43 which between them selves embrace the vane wheel so that merely very narrow interspaces 45, 47 are left open between said walls and the opposed plane end faces of the vane wheel. The shaft 17 extends through said Walls 41, 43 and is sealed thereto by means of stuffing boxes 49, 51.

The above-described casing further comprises a pulp inlet 53, a pulp outlet 55 and a bleaching agent inlet 57. The pulp inlet 53 ends with an orifice 59' in the wall 41, which orifice has the approximate configuration of a sector of the circular zone or annular area described by the edges 27 of the vanes. The extension of said sector corresponds to a centre angle of about to degrees. Therefore the remaining part of the wall 41 has the shape of a central complete circular area of a diameter equal to that of the hub 15, which over an angle of 240 to 180 degrees is integral with a circular sector of a greater diameter. The pulp inlet 53 is formed with a circular flange 59 for connection to a pulp supply conduit, the inlet constituting a somewhat curved transition piece, the cross-section of which gradually changes from circular shape to sector shape. The pulp outlet 55 is shaped similarly to the inlet and has a sector-shaped orifice preferably coextensive and situated opposite to the orifice 59 at the other side of the vane wheel.

The axially directed bleaching agent inlet 57 opens out into the Wall 41. The orifice 61 thereof is sector-shaped and extends transversely over the annular area of the wall swept over by the edges 27 of the vanes. The orifice 61 is elongated and the two long sides are radially directed.

The other plane wall 43 of the casing is formed with an aperture 63 located opposite to the orifice 61. Said aperture which is normally covered by a lid 65, makes it possible to move the bleaching agent inlet 57 to the other side when local conditions require, or to use two bleaching agent inlets simultaneously.

When pulp that is pumped in through the inlet 53 reaches the vane wheel, successive layers thereof will be caught by the vane edges 27 and forced to take part in the rotation of the vane Wheel. The axial extension of the vane wheel is so great that it is not possible for the pulp to follow the vane wheel merely with a reduced speed, which would involve agitation by the vanes. As the vane edges move past the sharp border edge of the orifice 59 and the wall 41, successive batches of the pulp will be confined into completely closed compartments formed between the vanes and the walls 41, 43, 37 of the casing, the pulp therefore being forced to sweep over the wall 41 at a rate accurately determined by the speed of rotation of the vane wheel. As the pulp batches are moved past the orifice 61, the bleaching agent is spread into the pulp with the correct radial distribution. After any particular pulp batch has followed the vane wheel during a number of revolutions, the same is pushed out through the pulp outlet 55, the continuous pressure feed of the pulp through the inlet 53 causing a step-wise axial displacement of the pulp confined between the vanes each time a particular compartment is placed between the opposed sector-shaped orifices of the pulp inlet and outlet.

I claim:

1. In apparatus for mixing of bleaching agents into cellulosic pulp, particularly high-density pulp, said apparatus being of a type having a casing enclosing a driven vane wheel which has a plurality of vanes disposed substantially radially about an axis of rotation of said vane wheel and including means for mounting and rotating the vane wheel within the casing, said apparatus further having a pulp inlet for admitting pulp axially between the vanes of the wheel in a sector of the vane Wheel, while it is rotating, so that pulp is carried between the vanes of the wheel during rotation of the wheel, the improvement comprising:

the casing having a plane wall perpendicular to the axis of rotation of the vane wheel and located closely to the vane wheel and laterally of the pulp inlet, said plane wall having an orifice therethrough for receiving bleaching agent which is admitted through an inlet into said casing, said vane wheel being arranged to move pulp along said plane wall and past the orifice of the bleaching agent inlet, said orifice of the pulp inlet having a configuration of a sector of the circular zone described by one end edge of each vane of the wheel, said sector extending over a centre angle of 120 to 180 degrees.

2. In apparatus for mixing of bleaching agents into cellulosic pulp, particularly high-density pulp, said apparatus being of a type having a casing enclosing a driven vane wheel which has a plurality of vanes disposed substantially radially about an axis of rotation of said vane wheel and including means for mounting and rotating the vane wheel within the casing, said apparatus further having a pulp inlet for admitting pulp axially between the vanes of the wheel in a sector of the vane wheel, while it is rotating, so that pulp is carried between the vanes of the wheel during rotation of the wheel, the improvement comprising:

the casing having a plane wall perpendicular to the axis of rotation of the vane wheel and located closely to the vane wheel and laterally of the pulp inlet, said plane wall having an orifice therethrough for receiving bleaching agent which is admitted through an inlet into said casing, said vane wheel being arranged to move pulp along said plane wall and past the orifice of the bleaching agent inlet, said bleaching agent inlet being axially directed with its orifice in said plane wall having the approximate configuration of a narrow sector of the circular zone of said wall swept over by the end edges of the vanes of the wheel.

3, In apparatus for mixing of bleaching agents into cellulosic pulp, particularly high-density pulp, said apparatus being of a type having a casing enclosing a driven vane wheel which has a plurality of vanes disposed substantially radially about an axis of rotation of said vane wheel and including means for mounting and rotating the vane wheel within the casing, said apparatus further having a pulp inlet for admitting pulp axially between the vanes of the wheel in a sector of the vane wheel, while it is rotating, so that pulp is carried between the vanes of the wheel during rotation of the wheel, the improvement comprising:

the casing having a plane wallrperpendicular to the axis of rotation of the vane wheel and located closely to the vane wheel and laterally of the pulp inlet, said plane wall having an orifice therethrough for receiving bleaching agent which is admitted through an inlet into said casing, said vane wheel being arranged to move pulp along said plane wall andpast the orifice of the bleaching agent inlet, said casing being provided with an outlet for pulp mixed with bleaching agent, the orifice of said outlet being opposite and coextensive to the orifice of the pulp inlet, and said casing further having a second plane wall laterally of said pulp outlet orifice and perpendicular to the axis of the vane wheel and situated closely up to the vane wheel.

4. Apparatus according to claim 3, characterized in that the vanes extend substantially radially and tangentially from the hub of the wheel, and have plane broad faces which are parallel to the shaft and of an axial extension dilfering very little from the distance between the two plane Walls of the casing.

References Cited UNITED STATES PATENTS 1,409,827 3/ 1922 Callahan 2597 2,514,254 7/ 1950 Paulus 259-9 FOREIGN PATENTS 100,006 5/ 1962 Norway.

WALTER A. SCHEEL, Primary Examiner.

JOHN M. BELL, Assistant Examiner. 

